Canvas stretcher

ABSTRACT

A stretcher for canvas or other flexible material, the stretcher being made by miter-cutting a profiled strip into four pieces which, when assembled into a frame, have the desired stretcher dimensions. The strip, preferably fabricated of lightweight metal or plastic of high structural strength, has a uniform crosssectional profile which defines a flat outer edge, a channel fillable with a compound for accepting and retaining tacks to secure the canvas thereto, a slot for accommodating right angle irons to interconnect the pieces and a key groove to receive wedges as well as reinforcing cross bars.

United States Patent Terna [4 1 Mar. 28, 1972 [541 CANVAS STRETCHER2,149,985 3/1939 Tepper ..l60/374.l 2,167,836 8/1939 Greulich ..52/376[72] Invent ,fififigf fifif m 89th Street 3,012,362 12/1961 Blinderman..l60/374 1 3,392,500 7/1968 Johnston ..52/376 X [22] Filed: Apr. 13,1970 [21] APPL NW 28,187 Primary Examiner-Darid J. WilliamowskyAssistant Examiner-Philip C. Kannan Related US. Application DataAttorney-Michael Ebert [63] Continuation of Ser. No. 792,244,Jan. 21,1969, now [57] ABSTRACT abandoned. [52] 1.1.5. C1 ..160/374.1, 52/376 Astretchgr for canvas or other flexible material the smrchcr [51] Int. Cl..B44d 3/18 being made by miter-curling a rofiled strip imo four iecesof Search which when assembled into a frame have he desired 52/3721 3751375 stretcher dimensions. The strip, preferably fabricated oflightweight metal or plastic of high structural strength, has a [56]References Cited uniform cross-sectional profile which defines a flatouter edge, UNITED STATES PATENTS a channel fillable with a compound foraccepting and retaining tacks to secure the canvas thereto, a slot foraccommodatmg 251,253 12/1881 Lazel'ges -160/374-l right angle irons tointerconnect the pieces and a key groove 10/1 Tait 1 to receive wedgesas we" as reinforcing cross bars. 1,847,925 3/1932 Carter ..l60/374.l2,049,907 8/ 1936 Hess ..52/375 6 Claims, 7 Drawing Figures CANVAS STRETCHER This is a continuation of application Ser. No. 792,244, filedJan. 21, 1969, now abandoned.

This invention relates generally to stretching frames for supportingcanvas and the like, and more particularly to a stretcher made from aprofiled strip which may be miter-cut to any desired size and quicklyassembled without the need for tongue and groove joints.

Conventional stretchers are constituted by a wooden frame onto which apiece of canvas or other textile material, such as silk, is marginallysecured by tacks or staples. By means of wedges or screws which areforced into the corners of the frame, the material is tautly stretchedin all directions across its expanse. Due to the slight give of the tautcanvas under pressure of the brush, canvas stretchers afford the artista good working surface.

It is presently the practice for art supply houses to stock pieces ofmolded wood whose ends are formed with complementary tongues andgrooves, so that the pieces may be readily assembled into stretchers. Inorder to make available a broad range of stretcher sizes, it isessential for the supply house to maintain a large stock of pieces inpredetermined dimensions. Usually, an art supply house must have aminimum of 37 distinct stretcher sizes if run-of-the-mill requirementsare to be satisfied.

There are several practical drawbacks to the existing supply system forstretchers. There may, for example, be an unexpected demand for aparticular stretcher size and, despite the large number of pieces onhand, one is yet not able to meet the need for the particular size. Onthe other hand, while the demand for other stretcher sizes may beinfrequent, one must nevertheless have those sizes in stock in order tomeet the demand when it does arise.

Hence even though an art supply house maintains a large and expensiveinventory of stretcher pieces, it often finds that its inventory isinadequate in that the demand for particular sizes is erratic andunpredictable. Moreover, where the requirement is for a non-standardsize, this demand cannot be met at all and the artist must arrange tohave the stretcher custom-made.

With the present tendency in the art world for artists to work on verylarge-scale canvases, existing stretcher inventories are incapable ofproviding the required dimensions and many artists are forced toimprovise their own stretchers. Unless a stretcher is professionallymade, the stretcher will not hold its proper form, and warpage,twisting, corner mismatch and change of angle are experienced which havedamaging effects on the painting. Existing stock stretchers have noprovision for cross pieces to reinforce the structure to maintain itsproper configuration.

It is not possible, in place of precut pieces, merely to have aninventory of long strips which can be miter-cut to size when an order isreceived, for it is also necessary with a conventional stretcher to havetongue and groove joints. It is neither practical nor feasible in an artsupply house to install equipment for cutting tongues and grooves, whichis the reason for the present practice of stocking factory precut pieceswhich incorporate these formations.

Accordingly, it is the main object of the present invention to provide aprofiled strip which may easily be cut into pieces of any desired sizeto form a stretcher without the need for tongue and groove joints.

Also an object of the invention is to provide a profiled strip of theabove type which may be fabricated of lightweight metal or plastic whichis free of warpage, dimensional instability and other drawbackscharacteristic of wood. It is to be understood, however, that theprofiled strip in accordance with the invention may be made of wood andstill have advantages over conventional wood stretchers.

Yet another object of the invention is to provide a stretcher which maybe manufactured and sold at relatively low cost, and which requiresrelatively little skill to assemble properly.

A significant feature of the invention is that substantially it reducesinventory requirements for art supply houses, for by stockingstandardized strips of the profiled material, one may supply an artistwith a stretcher of any specified size without the need to stock a broadrange of precut pieces. Moreover, one may supply non-standard as well asstandard stretcher sizes so that the artist is not limited in his workto existing stretcher dimensions.

Briefly stated, these objects are accomplished by a profiled strip whoseuniform cross-sectional shape defines a flat outer edge which forms theborder of the stretcher, a back channel which is fillable with acompound for accepting tacks to secure the canvas thereto, a front slotto accommodate right angle irons to join the pieces of the stretcher,and an inner key groove to receive stretching wedges as well asreinforcing cross bars.

For a better understanding of the invention, as well as other objectsand further features thereof, reference is made to the followingdetailed description to be read in conjunction with the accompanyingdrawing wherein:

FIG. 1 is a perspective front view of a stretcher in accordance with theinvention,

FIG. 2 is a transverse section taken in the plane indicated by lines 22in FIG. 1,

FIG. 3 is an exploded view of two pieces of the stretcher,

FIG. 4 is a plan view showing one corner of the stretcher, with thecanvas cut away to expose a stretching wedge,

FIG. 5 is a perspective rear view of the stretcher, showing thereinforcing cross bars therefor,

FIG. 6 shows, in exploded view, the manner in which one cross bar isinterfitted with another cross bar, and

FIG. 7 shows the manner in which a cross bar is interfitted with astretcher piece.

Referring now to the drawing and more particularly to FIGS. 1, 2 and 3,there is shown a stretcher in accordance with the invention which iscreated by miter-cutting a strip of profiled material into fourstretcher pieces 10, ll, 12 and 13 which, when joined together, form arectangular frame of the desired size. The ends of the pieces aremiter-cut at 45 so that when joined together, right angle corners areformed in the usual manner.

The profiled strip from which the pieces are cut may be made of extrudedaluminum or other lightweight material which is structurally stable andof high strength. The crosssectional profile of the strip, which canbest be seen in piece 13 in FIG. 3, is uniform such as to define a flatlongitudinal edge A, a rear channel B, a front slot C and an inner keygroove D, the channel slot and groove all lying in parallel relation tothe edge. Edge A forms the border of the stretcher frame over which isplaced a piece of canvas 14 or other paintable, flexible material suchas silk or paper.

The margins of canvas 14 are carried over flat edge A to overlie theback channel B. Channel B is filled with a suitable compound such asplastic wood, foam plastic or any other composition capable of acceptingand retaining tacks or staples or whatever other means are used tosecure the canvas to the stretcher. In FIG. 2, it will be seen that thecanvas is attached to the stretcher by tacks 15.

The flat edge A of the strip projects well above the body thereof, asbest seen in FIG. 2, to space the canvas 14 therefrom. Inasmuch as thestretched canvas, when subjected to brush pressure, gives somewhat, thisspacing acts to prevent the canvas from engaging the body of thestretcher pieces, and thereby prevents the formation of undesirableridge marks on the painted canvas.

Slot C is dimensioned to receive a right angle iron 16, as shown in FIG.3, one leg of the iron going into slot C of piece 13 and the other inslot C in piece 10 to join these pieces together, thereby obviating theneed for a tongue and groove connection. The angle irons initiallyprovide a loose connection of the pieces, but when the canvas isattached, the pieces are securely held together.

After the canvas is marginally secured to the stretcher, it is necessaryto stretch the surface thereof in all directions across its expanse. Forthis purpose, as shown in FIG. 3, wedges l7 are driven into the cornersof the pieces through the key grooves D. As will later be explained,these grooves have a "T shaped configuration defining a deep minorgroove and a broader major groove to accommodate cross pieces as well asthe wedges. To facilitate the wedging action, the grooves D, at thecorners of the minor grooves, may be beveled to form an entrance d intothe corner junction. As the wedges are driven in, the joined pieces tendto separate, thereby subjecting the canvas to tension. When the piecesseparate, they still maintain their proper right anglerelationship, forthe angle irons in slot C prevent angular displacement of the pieces.

As shown in FIG. 5, the stretcher may be reinforced by cross pieces toprevent bowing thereof or other undesirable dimensional changes. Suchreinforcement is generally only necessary in larger stretcher sizes. Inthe fairly elaborate arrangement shown, vertical cross pieces 18 and 19are interposed between the stretcher pieces and 12, while horizontalcross piece 20 is interposed between stretcher piece 11 and cross piece18, horizontal cross piece 21 is interposed between cross piece 18 andcross piece 19, and cross piece 22 is interposed between cross piece 19and stretcher piece 11, thereby providing an intersecting reinforcementpattern of high strength.

As illustrated in FIGS. 6 and 7, each cross piece, such as 18, has arectangular cross-sectional form, with channels C and C cut into theopposing long sides thereof. The width of channels C and C in the longsides is equal to the length of the short sides of the cross piece,thereby making it possible for the end of cross piece 21 to be insertedin channel C of cross piece 18, as shown in FIG. 6. Channels C and C areeach formed with a depressed subchannel to receive a wedge 17 to hold aninserted cross piece in place.

, The widthof the key groove'D in the stretcher piece 10, as shown inFIG. 7, is equal to the length of the long sides of the cross pieces, sothat the end of cross piece 18 may be inserted therein and locked inplace by wedges 17.

It is to be understood that the strip according to the invention is notlimited to the particular profile shown and that while in all cases thestrip must have a flat outer edge to provide the border, the placementand configuration of the channel' B for the compound,the slot C for theangle irons and the key groove for the stretching wedges may be variedto suit the use to what the stretcher is to be put.

It will be evident from the foregoing, that all the art supply houseneed store is a stock of long profiled strips in any suitable standardsize, and strips of cross piece material, and when an order for aparticular stretcher dimension is received, it is only necessary to cutthe strips into pieces of the requisite size.

Thus while the stretcher has been disclosed herein as intended forcanvas, it is usable also with silk screens and watercolor paper as wellas with materials having a more limited stretch, such as leather,cardboard and metal foil. The channel vB for the tack-receiving compoundneed not be on the back of the pieces, and may in some instances beformed in border A on the front side thereof, this arrangement beinguseful for silk screen s.

I claim: 1. A stretcher for a canvas or other flexible material, saidstretcher comprising:

' A. four side pieces which are miter-cut from a profiled strip of blockmaterial to form a rectangular frame to support said canvas, said striphaving a cross-sectional profile 4 which is uniform throughout itslength and is contoured to define the following elements extending thefull length of the strip;

a. a flat outer edge forming the border of the stretcher,

b. a channel fillable with a compound for accepting and retaining tacksor other means to secure the margin of the canvas thereto,

0. a slot for receiving right angle elements, and

d. a key groove having a T-formation defining a depressed minor grooveto receive wedges and a broader major groove to receive the ends ofcross pieces whose width is substantially the same as the width of themajor groove,

B. four right angle elements inserted in the slots of said pieces tointerconnect same to form the corners of the stretcher,

C. at least one cross piece extending between opposed side pieces of thestretcher, the ends of said cross piece being received within the majorgrooves of said side pieces, and

D. wedges inserted in the minor grooves of the side pieces at thecorners of the stretcher to tension the canvas supported thereon, andinserted in the minor grooves of. the side pieces adjacent the ends ofsaid cross piece to secure the cross piece thereto.

2. A stretcher as set forth in claim 1, wherein said edge, said channel,said slot and said groove all lie in parallel relation,

said channel being at the back of the strip and said slot at th frontthereof.

3. A stretcher as set forth in claim 1, wherein said compound haswood-like characteristics.

4. A stretcher as set forth in claim 1, wherein said strip is formed ofextruded aluminum.

5. A stretcher as set forth in claim 1, wherein said flat edge isdimensioned to space the canvas secured to said stretcher away from thebody of said pieces.

6. A stretcher for a canvas or other flexible material,.said stretchercomprising:

A. four side pieces which are miter-cut from a profiled strip of blockmaterial to form a rectangular frame to support said canvas, said striphaving a cross-sectional profile which is uniform throughout its lengthand is contoured to define the following elements extending the fulllength of the strip;

a. a fiat outer edge forming the border of the stretcher,

b. a slot for receiving right angle elements, and

c. a key groove having a T-formation defining a depressed minor grooveto receive wedges and a broader major groove to receive the ends ofcross pieces whose width is substantially the same as the width of themajor groove,

B. four right angle elements inserted in the slots of said pieces tointerconnect same to form the corners of the stretcher,

C. at least one cross piece extending between opposed side pieces of thestretcher, the ends of said cross piece being received within the majorgrooves of said pieces, and

D. wedges inserted in the minor grooves of the side pieces at thecorners of the stretcher to tension the canvas supported thereon, andinserted in the minor. grooves of the the cross piece thereto.

1. A stretcher for a canvas or other flexible material, said stretchercomprising: A. four side pieces which are miter-cut from a profiledstrip of block material to form a rectangular frame to support saidcanvas, said strip having a cross-sectional profile which is uniformthroughout its length and is contoured to define the following elementsextending the full length of the strip; a. a flat outer edge forming theborder of the stretcher, b. a channel fillable with a compound foraccepting and retaining tacks or other means to secure the margin of thecanvas thereto, c. a slot for receiving right angle elements, and d. akey groove having a T-formation defining a depressed minor groove toreceive wedges and a broader major groove to receive the ends of crosspieces whose width is substantially the same as the width of the majorgroove, B. four right angle elements inserted in the slots of saidpieces to interconnect same to form the corners of the stretcher, C. atleast one cross piece extending between opposed side pieces of thestretcher, the ends of said cross piece being received within the majorgrooves of said side pieces, and D. wedges inserted in the minor groovesof the side pieces at the corners of the stretcher to tension the canvassupported thereon, and inserted in the minor grooves of the side piecesadjacent the ends of said cross piece to secure the cross piece thereto.2. A stretcher as set forth in claim 1, wherein said edge, said channel,said slot and said groove all lie in parallel relation, said channelbeing at the back of the strip and said slot at the front thereof.
 3. Astretcher as set forth in claim 1, wherein said compound has wood-likecharacteristics.
 4. A stretcher as set forth in claim 1, wherein saidstrip is formed of extruded aluminum.
 5. A stretcher as set forth inclaim 1, wherein said flat edge is dimensioned to space the canvassecured to said stretcher away from the body of said pieces.
 6. Astretcher for a canvas or other flexible material, said stretchercomprising: A. four side pieces which are miter-cut from a profiledstrip of block material to form a rectangular frame to support saidcanvas, said strip having a cross-sectional profile which is uniformthroughout its length and is contoured to define the following elementsextending the full length of the strip; a. a flat outer edge forming theborder of the stretcher, b. a slot for receiving right angle elements,and c. a key groove having a T-formation defining a depressed minorgroove to receive wedges and a broader major groove to receive the endsof cross pieces whose width is substantially the same as the width ofthe major groove, B. four right angle elements inserted in the slots ofsaid pieces to interconnect same to form the corners of the stretcher,C. at least one cross piece extending between opposed side pieces of thestretcher, the ends of said cross piece being received within the majoRgrooves of said pieces, and D. wedges inserted in the minor grooves ofthe side pieces at the corners of the stretcher to tension the canvassupported thereon, and inserted in the minor grooves of the side piecesadjacent the ends of said cross piece to secure the cross piece thereto.